There are a number of devices available for traveling through pipes, but none of these devices or travelers can turn corners selectively, that is, where there is a sharp corner or more than one option. Others can turn but only when the pipe itself makes a turn without any other options or branches. A separate problem is designing travelers which can climb and descend steep or vertical pipes as well as adapt to travel through pipes of widely ranging sizes and locally irregular sizes and shapes. For example, those tractors which are small enough to travel through many different sized, larger and larger pipes have no way of establishing traction to ascend or descend steep or vertical pipes. Some such travelers work only in pipes of specific material, e.g., ferromagnetic pipes. Some travelers cannot be used in live systems because they block the fluid flow.